One of Motorola’s most vocal shareholders raised his stake in the company to 8.75 percent, according to documents filed with the SEC.

The activist investor now owns 203.32 million shares of Motorola, up from the 119.8 million shares he owned at the end of last year.

Icahn believes Motorola will become more valuable after it completes a break-up plan early next year, according to an anonymous source cited by The Wall Street Journal.

Icahn first acquired a stake in Motorola in 2007 and has since pushed the company to move forward with a plan to spin off its various divisions, which are comprised of its networks, enterprise mobility, mobile device and set-top box units.

Icahn pushed Motorola for an appointment to its board of directors, a proposal that was voted down by a stockholder vote. He later sued Motorola as part of an effort to gain four seats on the company’s board and force the company to spin off its handset division.

Motorola eventually placed two of Icahn’s recommended directors on its board.

In February, Motorola announced changes to its previously announced break-up plan that would split Motorola into two independent, publicly traded companies by the first quarter of 2011.

Under the new plan, Motorola said its devices and set-top box units would be combined into one company while its enterprise mobility and networks divisions would be combined into another. Motorola said at the time it would use a tax-free stock dividend of shares in the new company to complete the separation.